Triangular joist



y 1941- A. 1. RUBIN. 2,241,617

TRIANGULAR JOI ST Filed July 27, 1940 37 TEE 37 km 31 3235 3319 an; as

INVENTOR. I. R u a: N

ATTORNEY.

Patented May 13, 1941 i'i" STA TRIANGULAR JOIST Allen I. Rubin, Mount Vernon, N. Y. Application July 2'2, 194:0, Serial No. 347,855

7 Claims.

This invention relates to metal joists or girders for use in building construction and other general types of construction.

More particularly, this invention relates to a type of metal joist of a triangular cross section having longitudinal members and separately formed lacing or lattice units extending between the longitudinal members and forming diagonal trussing.

An object of my invention is to provide a metal joist or supporting beam which is of new and improved construction and in which the lacing is so formed and positioned as to give the maximum capacity and lateral stiffness to the J'oist.

Another object of my invention is to provide a joist that will effect a saving in construction by eliminating or minimizing bridging, requiring fewer pieces to erect thus saving handling and labor costs.

An object of my invention is to provide a metal joist by the use of which the fioor or roof construction need not be relied upon for lateral stiffness, and wherein the joists may be spaced farther apart, thus saving on installation costs and increasing the speed in construction.

Another object of my invention is to provide a new type of metal joist of substantially triangular cross-section which will lend itself to a unique type of ceiling construction and floor system.

With the above and other objects in view, the invention will be hereinafter more particularly described, and the combination and arrangement of parts will be shown in the accompanying drawing and pointed out in the claims which form part of this specification.

Reference will now be had to the drawing, wherein like numerals of reference designate corresponding parts throughout the several views, in which:

Figure 1 is a side elevation of a metal joist constructed in accordance with the present invention.

Figure 2 is a top plan view of the joist shown in Figure 1.

Figure 3 is a cross-sectional view, the section being taken as on line 3-3 in Figure 1.

Figure 4 is a cross-sectional view, the section being taken as on line 4-4 in Figure 2, showing welded corners.

Figure 5 is a cross-sectional view similar to that shown in Figure 4, showing integral rightangular side members.

Figure 6 is a cross-sectional view similar to that shown in Figure 4, showing Welded bearing plates.

Figure 7 is a fragmentary ing modified braces.

Figure 8 is a fragmentary top plan View showing another form of braces.

Figure 9 is a fragmentary top plan view showing another form of braces.

Figure 10 is a cross-sectional view, the section being taken as on line ill-10 in Figure 9.

Figure 11 is a fragmentary end portion of a modified metal joist showing the lower chord shorter than the upper chord.

Figure 12 is a cross-sectional view, the section being taken as on line [2-42 in Figure 11.

Figure 13 is a fragmentary top plan view of the metal joist shown in Figure 11.

In the illustrated embodiment of the invention, the numeral l0 indicates my improved metal joist comprising a lower chord member H and an upper chord member l2 with reinforcing and connecting means therebetween. The connecting means preferably comprises a plurality of longitudinally spaced diagonal bracing l3.

The lower chord member II is of inverted T- shape. The upper chord member l2 comprises two elongated angle members It disposed in spaced-apart relation. The upper and lower chord members are connected to the diagonal bracing preferably by welding the upper and lower surfaces of the braces to the said chord members, the horizontal flanges of the angle members being disposed in the same horizontal plane. The angle members I4 of the upper chord member are joined by connecting bracing I5 by welding.

As shown in Figure 3, the angle members l4 have also been welded to angular bearing members [6, respectively having one of their legs in the same horizontal plane as'indicated by the numeral ll. As shown in Figures 1 and 3, it will be noted that the lower chord member H has been bent upwardly at its end portions towards the upper chord member l2, as shown at I8, leaving horizontal portions or extensions l9- which are welded at their side edges to the said bearing legs I1, and forming a continuous bearing plate 20 at each end of the joist l0, whereby the joist may be supported upon a horizontal building support at each end thereof. The supports 2| may be abutments of a building, main girders, or other members adapted for carrying joists of the type herein disclosed.

Figure 4 shows a modified form of bearing portion 25 for the joist, wherein a bearing plate 26 top plan view showmembers 5i and diagonal overlapping braces the bottom chord.

extends across the entire width of the top chord. Vertical plates 2's" are welded to the angles l4 and to the bottom plate 25. The horizontal extension is of the inverted T-shaped lower chord rests on the upper surface of the bearing plate 26 and is welded thereto.

Figure 5 shows a modified form of bearing portion 36 for the joist, wherein the web plate 3i of a channel 82 extends across the entire width of the top chord of the joist. The vertically position d flanges 3 of the channel o2 are welded to the angles M. The horizontal extension is of the inverted T-shaped lower chord rests on the upper surface of the web plate 3! and is welded thereto.

Figure 6 shows a modified form of bearing portion 35 for the joist, wherein angular bearing members 35 have legs 3? positioned vertically and being welded to the angles it. The members 35 have the edges of their horizontal legs 38 welded to the side edges of the horizontal extension i9 of the inverted T-shaped lower chord. The bearing portion 35 is similar to that shown in Figure 3, but with the angle i i not joined by horizontal bracin Figure '7 is a fragmentary top View of a modified top chord d3 built in the form of a Pratt truss having a pair of angle members t! and connecting members Q2, and in which each principal member is subject to stress only in the direction of its length.

Figure dis a fragmentary top plan view of a modified top chord 15 built in the form of a Warren truss, having a pair of members and connecting members il.

Figure 9 is a fragmentary top plan view of a modified top chord having a pair of angle syll- Figure 10 is a cross sectional view, the section being taken as on line liE-i5 in rgure 9, showing the overlapping braces 52 as bein of round cross-section.

Figure 11 is a fragmentary side elevation of a modified joist in which the lower chord 55 is shorter than the upper chord til, the said chords being parallel throughout their lengths. The chords are welded to connecting members cl and 58. The members 53 are at both ends of the joist and are heavier than the members Figure 12 is a cross-sectional View, the section being taken on line in Figure 11, on an enlarged scale.

Figure 13 is a fragmentary the joist shown in Figures 11 and 12.

Refer ing to Figures 1, 2, 3, the joists can be considered and designed to carry superimposed vertical loads as two trusses with separate top chords it and common bottom chord H. The tensile stress in the top plan view of bottom chord will equal twice the stress in the bottom chord of one theoretical truss, providing that the joist is loaded symmetrically. If the joist is loaded eccen rically the diagonal bracing is at the lower chord intersection must be designed to carry the excessive horizontal component of the compressive stress so as to prevent any fiexural stresses in The tensile stress in the bo tom chord will then be the sum of the stresses in each theoretical bottom chord.

Figures '7, 8, 9 illustrate a trussed top chord F to eliminate bridging and maintain lateral stiffness. It is designed asa truss to withstand a possible temporary load during uilding construction of 560 lbs. applied laterally. In this case one longitudinal member as ti on Fig. 7,

or ll) on Fig. 8, or 55 on Fig. 9 of the top chord will be in compression and the other in tension.

In accordance with the patent statutes I have described and illustrated the preferred embodiments of my invention, but it will be understood that various changes and modifications can be made therein without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. A metal joist of triangular cross section comprising a lower chord made of an inverted T-shaped member, said lower chord being bent upwardly at its end portions and having horizontal end extensions, an upper chord including two elongated and spaced-apart angle members having legs positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising angular bearing members positioned externally of said elongated angle members and havirr legs positioned in a horizontal plane below said upper surface, the legs of said horizontal bearing members being welded to said horizontal end extensions and forming a continuous bearing plate at each end of said joist, and means for bracing said upper and lower chords.

2. A metal joist of triangular cross section comprising a lower chord made of an inverted T-shaped member, said lower chord being bent upwardly at its end portions and having horizontal end extensions, an upper chord including two elongated and spaced-apart angle members and lateral connecting members forming a truss, said angle members having legs positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising angular bearing members positioned externally of said elongated angle members and having legs positioned in a horizontal plane below said upper surface, the legs of said horizontal bearing members being welded to said horizontal end extensions and forming a continuous bearing plate at each end of said joist, and means for bracing said upper and lower chords.

3. A metal joist of triangular cross-section, said triangle having two of its sides equal and being inverted with its base in upper position, said metal joist comprising a lower chord made of an inverted T-shaped member, said lower chord being bent upwardly .at its end portions and having horizontal end extensions, an upper chord including two elongated and spaced-apart angle members and lateral connecting members forming a truss, said angle members having legs positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising angular bearing members positioned externally of said elongated angle members and having legs positioned in a horizontal plane below said upper surface, the legs of said horizontal bearing members being welded to said horizontal end extensions and forming a continuous hearing plate at each end of said joist, and means for bracing said upper and lower chords.

4. A metal joist of triangular cross-section, said triangle having two of its sides equal and being inverted with its base in upper position, said metal joist comprising a lower chord made of an inverted T-shaped member, said lower chord having horizontal end extensions, a trussed top chord including two elongated and spacedapart angle members having legs positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising angular bearing means positioned in a horizontal plane below said upper surface, said bearing means being welded to said horizontal end extensions and forming a continuous bearing plate at each end of said joist, and means for bracing said upper and lower chords.

5. A metal joist of triangular cross-section, said triangle having two of its sides equal and being inverted with its base in upper position, said metal joist comprising a lower chord made of an inverted T-shaped member, said lower chord having horizontal end extensions, a trussed top chord including two elongated and spacedapart angle members having legs positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising bearing means positioned in a horizontal plane below said upper horizontal plane, and means for bracing said upper and lower chords.

6. A metal joist of triangular cross-section and :being inverted with its base in upper position, said metal joist comprising a lower chord made of an inverted substantially T-shaped member, said lower chord having horizontal end extensions, a trussed top chord including two elongated and spaced-apart members having portions thereof positioned in a horizontal plane forming the upper surface of said joist, said upper chord comprising bearing means positioned in a horizontal plane below said upper horizontal plane, and means for bracing said upper and lower chords.

'7. A metal joist of triangular cross-section and being inverted with its base in upper position, said metal joist comprising a trussed top chord, a lower chord spaced apart from said top chord and having horizontal end extensions, said top chord including two elongated and spaced-apart members having portions thereof positioned in a horizontal plane forming the upper surface of said joist, said .top chord comprising substantially U-shaped bearing means, the legs of said U-shaped bearing means being secured to said spaced-apart members, and means for bracing said upper and lower chords, said bracing being welded to said upper and lower chords.

ALLEN I. RUBIN. 

